ML20101L697
| ML20101L697 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 12/28/1984 |
| From: | Schnell D UNION ELECTRIC CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20101L699 | List: |
| References | |
| ULNRC-1003, NUDOCS 8501020343 | |
| Download: ML20101L697 (7) | |
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UNION EECTRIC COMPANY 1901 Grotlot Street, St. Louis Donoki F. Schnell Vice President December 28, 1984 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D. C.
20555
Dear Mr. Denton:
ULNRC-100 3 DOCKET NUMBER 50-483 CALLAWAY PLANT, UNIT 1 CALLAWAY LICENSE CONDITION C (12)
The attachments to this letter provide our response to Callaway Facility Operating License NPF-30, License Condition C(12) regarding low temperature overpressure protection.
This information was previously discussed with members of your staff in a meeting on November 27, 1984.
t Please contact us if additional information is required.
As specified in the subject license condition, the plant modifications described in the attachments will be made within one year of receiving NRC approval.
V truly yours, W
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Lu-h Donald T. ' chnell DS/bjk Attachments I
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P Mailing Address: RO Box 149, St. Louis, MO 63166
STATE OF MISSOURI )
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Robert'J. Schukai, of lawful age, being first' duly sworn upon oath'says that he is General Manager-Engineering - (Nuclear) - for Union Electric Company; that he has read the foregoing document and-knows the content thereof; that he has executed the same for and on behalf of said company with full power and authority to do-so; and that the facts therein stated are true and correct to the best of his knowledge, information and belief.
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U Robdr t J'.~ Schpkai General M er-Engineering Nuclear SUBSCRIBED and sworn to before me this,2ffA day of decem Acr, 198f n0 MARY C. GUINN NOTARY PtlBLIC-STATE OF MISSOURI ST. LOUIS CITY, MY COMMISSION EXPlRES JUNE 16, 1906
cc:
Gerald Charnoff, Esq.
Shaw, Pittman, Potts & Trowbridge 1800.M. Street, N.W.
Washington, D.C.
20036 Nicholas A.
Petrick
-Executive Director SNUPPS S Choke Cherry Road Rockville, Maryland 20850 John H. Neisler Callaway Resident Office U.S. Nuclear Regulatory Commission RRil Steedman, Missouri 65077 William Forney Division of Projects and Resident Programs, Chief, Section lA U.S. Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, Illinois 60137 Bruce Little Callaway Resident Office U.S. Nuclear Regulatory Commission RRil Steedman, Missouri 65077 Jan Stevens Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop P-316 7920 Norfolk Avenue Bethesda, MD 20014 4
m Attachmznt I to s
ULNRC-1003 This information is being provided in response to license condition C(12) of Facility.0perating License NPF-30 for Callaway Plant, Unit I which states:
(12) Low Temperature Overpressure Protection (Section 15, SSER #3)
By January 1, 1985, UE shall submit for NRC review and approval a description of equipment modifications to the residual heat removal system (RHRS) suction isolation valves and'to closure circuitry which conform to the applicable staff requirements (SRP 5.2.2).
Within one year of receiving NRC approval of the modifications, UE shall have the approved modifications installed. Alternately, by January 1, 1985, UE shall provide acceptable justification for reliance on administrative means alone to meet the staff's RHRS isolation requirements, or otherwise, propose changes to Appendix A to this license which remove reliance on the RHRS as a means of low temperature overpressure protection.
In taking credit for the RHRS suction isolation valves for Cold Over-pressurization Protection, there are two Standard Review Plan (SRP) sections and two Branch Technical Positions which must be addressed.
These are SRP 5.2.2 "0VERPRESSURIZATION PROTECTION" and its associated Branch Technical Position RSB 5-2 "0VERPRESSURIZATION PROTECTION OF PRESSURIZED WATER REACTORS WHILE OPERATING AT LOW TEMPERATURES" and SRP 5.4.7 " RESIDUAL HEAT REMOVAL (RHR) SYSTEM" and its associated Branch Technical Position RSB 5-1.
A discussion of compliance with these positions follows.
I.
STANDARD REVIEW PLAN 5.2.2 AND BRANCH TECHNICAL POSITION RSB 5-2 The SNUPPS plants have been reviewed against these criteria and been found to have an acceptable design by use of the primary PORV's for a Low Temperature Overpressure Protection System (LTOPS) (Callaway SER Supplement #3, Section 5.2.2).
When relying i
on the RHRS suction relief valves for LTOPS, the literal requirement of Branch Technical Position RSB 5-2 B.9 is not met.
This section states:
"If pressure relief is from a low pressure system, not f
normally connected to the primary system, the over-l pressure protection function should not be defeated by l
interlocks which would isolate the low pressure system from the primary coolant system.
(See BTP ICSB3)"
Interlocks are provided on these valves to meet the requirements of l
SRP 5.4.7.
However, as shown in our February 10, 1984 letter and as described in the bases for the Callaway Plant. Technical Speci-fications Section B3/4.4.9 which states:
"The OPERABILITY of two PORVs. or wo PHR suction relief valves, or an RCS vent or "a 4.'
it least 2 square inches ensures that the cc w!,
c e protected from
2 pressure transients which could exceed the limits of Appendix G to 10 CFR Part 50 when one or'more of the RCS cold legs are less than or equal.to 368*F.
Either one PORV or one RHR suction relief valve has adequate reitev-ing capability to protect'the RCS from overpressurization when the transient is limited to either:
(1) the tart of an idle RCP with the secondary water temperature of the steam generator less than or equal to 50*F above the RCS cold leg temperatures, or (2) the start of a centrif-ugal charging pump and its injection into a water-solid RCS.
RHR/RCS suction isolation valves 8701A and B are inter-locked with an "A" train wide range pressure transmitter and valves 8702A and B are interlocked with a "B" train wide range pressure transmitter. Removing power from valves 8701B and 8702A, prevents a single failure from inadvertently isolating both RHR suction relief valves while maintaining RHR isolation capability for both RHR flow paths."
It is apparent that no single failure will cause isolation of both trains and the worst case overpressurization transient will not challenge the pressure interlock setpoint. Therefore, it is our position that the intent of SRP 5.2.2 and Branch Technical Position RSB 5-2 is met.
II.
STANDARD REVIEW PLAN 5.4.7 AND BRANCH TECHNICAL POSITION RSB 5-1 Branch Technical Position RSB 5-1 Sections B.l(a) and (c) (refer-enced in SRP 5.4.7) state:
i B.
RHR System Isolation Requirements l
The RHR system shall satisfy the isolation requirements listed below.
1.
The following shall be provided in the suction side of the l
RHR system to isolate it from the RCS.
(a)
Isolation shall be provided by at least two power-operated valves in series.
The valve positions shall be indicated in the control room.
(b) The valves shall have independent diverse interlocks to protect against one or both valves being open during an RCS increase above the design pressure of the RHR system.
During the period when one valve in each train is locked open as discussed in I. above, the requirements of this SRP are not met.
l This SRP, however, did not consider use of the RHRS suction relief valves for LTOPS. To ensure the RHRS is isolated from the RCS, administrative controls have been implemented which verify power is
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restored to valves BB-PV-8702A and EJ-HV-8701B and the valves are closed prior to exceeding the RHRS suction relief setpoint. Once power is restored, the interlocks are no longer defeated and full compliance with this SRP is're-established. Although Union
- Electric deems these controls adequate to demonstrate compliance with the intent of RSB 5-1 and RSB 5-2 (i.e. no single failure can result in the isolation of both RHR suction relief valves, available overpressure _ transient initiators will not result in activation of the pressure interlock, and~a plant procedure requires closing all RHR suction isolation valves when realigning RHR to the standby mode), we are pro' posing the design change shown in Attachment 2 as a means of more fully meeting the intent of these Branch Technical Positions.
III. DESCRIPTION OF PROPOSED PLANT MODIFICATION This modification would add an alarm circuit to valves BB-PV-8702A and EJ-HV-8701B such that if the valves are open or-do not have power available and the interlock activation setpoint is reached,
-the alarm would initiate on the main control board. As is true for all main control board annunciators, an annunciator alarm response procedure would be generated for this alarm. This procedure would require closing or verifying closure of the affected RHR suction isolation valves. This combination of annunciator / annunciator response procedure coupled with the administrative controls already in place provide a more positive means of protection for the RHR system than the current design. That conclusion is based on the following items.
i 1.
Removing power (defeating the interlocks) not only protects the RCS from a single failure causing isolation of both RHRS suction relief valves (loss of LTOPS) but also provides protection for both RHR pumps when in operation, from a loss of suction due to a single pressure transmitter failure.
Inadvertent isolation of the RHR suction valves has been a concern at other plants and has resulted in damage to one RHR pump at Callaway. This concern was also addressed by NRC Inspector P. R. Wohld in inspection report number 50-483/84-09(DE) where he recommended locking all RHR suction valves open in Modes 5 and 6.
l 2.
Although the interlocks are reliable, there is no visual indication in the control room (other than valve position indication) that the interlocks have closed the valve.
Therefore, if a signal is generated to close the valve and the l
valve fails to close, the operator would not be alerted. With l
the alarm circuit installed, if the valve is open or if power is not available and the pressure setpoint is reached, an alarm is generated in the control room giving the operator positive indication. Therefore protection is afforded if the operator fails to restore power or if the interlock actuates and the valve fails to close. Additionally, alarm responst procedures would provide positive operator actions.
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Since.it'is not probable that both valves in the system would remain open and~ undetected during a normal startup due to other indications-(i.e. relief valves lifting, PRT level, pressure and temperature alarms) and since it has been shown that no credible transient would challenge the interlock setpoint, the interlock would only function to shut a valve if one valve in the train were already closed. Therefore it is considered acceptable to use an alarm versus an interlock since operator response time would be sufficient to prevent operation at full RCS temperature and pressure with only single valve protection for the RHR system.
IV.
CONCLUSION Based on the discussions'above, it is the position of Union Electric that reliance on the administrative controls with the addition of the alarm circuits on valves BB-PV-8702A and EJ-HV-8701B not only meets the intent of SRP 5.4.7 but in actuality provides more protection for both the RCS (LTOPS) and the RHR system than the interlocks.
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